Typical race horseshoes are lightweight, made of a minimum of material and have a single calk at the forward end. This calk provides the primary means by which the horse achieves traction in the turf. One of the problems with such horseshoes is that they provide a minimum means for achieving such traction.
A second calk was added as an accessory to the horseshoe by means of a plate positioned between the horse's hoof and the hoof contacting surface of a conventional race horseshoe. This plate covered only a portion of the horse's hoof and therefore required shims between the horse's hoof and the horseshoe in those areas not covered by the plate to build up the thickness of the horseshoe equal to the thickness of the plate so that the horseshoe could be nailed over the plate along a level plane adjacent the horse hoof attachment surface. This means for including the second calk was inadequate in that a multiplicity of parts and individual forming of the parts were required in addition to forming the horseshoe when mounting on a hoof, the maintenance of horseshoe/hoof alignment was difficult in that relative movement between the plate, horseshoe and hoof frequently occurred and most significant the second calk could not be removed and replaced without the removal of the horseshoe. This made selective removal and replacement of the second calk for different track conditions or for any other reason virtually impossible.
A horseshoe with a selectively removable second calk as an integral part thereof was not available until the emergence of the instant invention.